The present invention relates to a method for anti-skid brake control for performing anti-skid brake control based on a friction coefficient .mu. (herein) after simply referred as ".mu.") during braking, judged on road surface, and in particular to a method for judging a friction coefficient of a road surface through behavior of wheel speeds during braking and also to a method for adequately performing anti-skid brake control based on the .mu. value, which has been judged by the above judging method.
Anti-skid brake control is generally performed as follows: When it is detected that the wheels are in a skid condition during braking, the braking force on the wheels is decreased to eliminate the skid condition. By increasing the braking force again thereafter, the steering of the vehicle is stabilized and the braking distance is made as short as possible.
In this anti-skid brake control, a control value of brake fluid pressure varies according to the .mu. value of the road surface where the vehicle is running and behavior of the wheel speeds against the change of the fluid pressure changes. Thus, it is necessary to perform anti-skid brake control giving full consideration on the value of .mu. of road surface.
Anti-skid brake control has been performed to match either a road with low .mu. value or a road with high .mu. value, or it has been performed commonly for both of a road with low .mu. value and a road with high .mu. value.
However, in such conventional anti-skid brake control, anti-skid brake control is performed commonly for both low a .mu. value and high .mu. value. Thus, the anti-skid brake control is not always adequately performed for the road with a low .mu. value and the road with a high .mu. value, and the control is not compatible with both of a low .mu. road and a high .mu. road.